Rotor for thin-layer vaporizers



ROTOR FOR THIN-LAYER VAPORIZERS 5: INVENTOR E a Mm BY www m ATTORNEYS Dec. 28, 1965 B. THlER 3,225,817

ROTOR FOR THIN-LAYER VAPORIZERS Filed May 6, 1963 5 Sheets-Sheet 5 INVENTOR i [gin/14.4

BY EWLVW -W ATTORNEYS United States Patent 3,225,817 ROTOR FOR THIN-LAYER VAPORIZERS Bernd Thier, Marl, Germany, assignor to Chemische Werke Huls Aktiengesellschaft, Marl, Germany, a corporation of Germany Filed May 6, 1963, Ser. No. 278,119

Claims priority, application Germany, Mar. 23, 1963,

9 Claims. (Cl. 159-6) Several types of thin-layer or film Vaporizers have been proposed which differ from each other principally by the manner in which the film is formed on the inner wall of the vaporizer body. For example, thin-layer vaporizers are known where the film is produced by rotating wipers, blades or similar means. However, blades which run in close proximity to but do not touch the wall and which have a certain ventilating effect cannot remove highly viscous or solid substances which form crusts on the wall. On the other hand, rubbing wipers can damage the vaporizer wall by creation of groovings and the like, especially if poorly lubricating materials are involved. Roller-shaped distributors, also preferred heretofore, will cause only slight wear of the vaporizer wall but will usually not remove viscous or solid substances from the wall.

In case of the thin-layer vaporization, employed in connection with purification and condensation processes as well as in connection with molecular distillation, viscous or solid deposits will form on the vaporizer wall and in many instances will interfere with further uniform film formation and vaporization and must therefore be removed. In these cases a device is required which will facilitate a uniform distribution of the liquid to be vaporize-d on the vaporizer wall and also the removal of deposits without causing any abrasion of the wall.

It has been found that these requirements can be met by revolving and rolling or sliding distributors which are in the form of elastic, oscillating flexible shafts. A particularly simple and advantageous arrangement for the distribution of liquid on and the removal of adhering substances from the wall of a thin-layer vaporizer is a device consisting of a rotor with taut springs arranged at the periphery of the rotor and moving in close proximity to the inner wall of the vaporizer and enclosed by sleeves, each spring and sleeve being free to oscillate. Taut springs in the meaning of the invention are coiled wires made of metals, plastics or similar materials which are able to oscillate resiliently in stretched state. Preferably, steel wires of suitable thickness, stretched or wound to form a coil spring are utilized.

The sleeves can be made of metals but it is more advantageous to use materials with good sliding ability, preferably synthetics such as polytetrafluoroethylene or graphite.

The invention is illustrated in the accompanying drawings in which FIG. 1 is a vertical section of an evaporator in accordance with the invention,

FIG. 2 is a cross section of the vaporizer shown in FIG. 1, on the line 2-2 of FIG. 1,

FIG. 3 is a vertical section of a vaporizer similar to that shown in FIG. 1 but having a modified form of sleeve,

FIG. 4 is a vertical section of a vaporizer showing a modification of the arrangement of the springs in the sleeves,

FIG. 5 is a vertical section of a vaporizer in which the springs are wound around the sleeves, and

FIG. 6 is a vertical section of a form of vaporizer in which the central shaft is replaced by spaced rods thus providing an open chamber within the vaporizer.

In the drawings like parts are marked by the same reference numerals.

FIGURE 1 shows the longitudinal cross section of a thin-layer vaporizer where the resilient oscillating distributing and wiping means are designed as coil springs with sleeves slid over the springs. Within a vaporizer tube 1, heated externally by a jacket 2, is a rotary assembly comprising a shaft 3 which is provided at top and bottom with hearing arms 4. The coil springs 5 are fastened to the arms 4 and are arranged in such manner that they are kept under tension. The sleeves 6 are pushed over the coil springs 5. The sleeves 6 are arranged concentrically to the coil springs 5 so that they will roll on the vaporizer tube 1 in case of a loose fit or will slide on said tube in case of a tight fit or are held against rotation for example by pinning.

Such a rotor assembly will cause, by its rotation, a complete and uniform distribution of flowing substances on the inner surface of the vaporizer tube 1. The outstanding uniformity of the distribtuion is attained primarily by the resilient mounting "of the sleeves 6.

When a flowing substance is being transformed into a viscous or solid and adhering mass due to the progressive vaporization, the uniform rolling or sliding of the sleeves 6 will become disturbed because the deposited material loses its lubricating properties and the individual oscillating flexible shafts or axles, consisting of coil springs 5 and sleeves 6, will being to vibrate independently of each other and beat upon the surface of the vaporizer tube. Thereby the adhering substances are distributed and moved in a very effective manner. Particularly advantages is the fact that the oscillations and consequently the beating on the Wall will increase in intensity if the substance becomes more viscous or more adherent and due to the quickly oscillating impacts even solid and strongly adhesive substances are removed within a short period of time.

FIGURE 2 shows a cross section of the vaporizer of FIG. 1. F our coil springs 5 with sleeves 6 are illustrated but it is possible to employ less, for example three, or more, for example eight, of such oscillating axles. Six or less oscillating axles will usually be sufficient in case of substances which flow easily or vaporize without residues while twelve or more oscillating axles are preferable in case of substances which are highly viscous or form hard and very adhesive deposits.

A very substantial advantage is the excellent self-centering of the rotor which eliminates the need for a lower bushing of shaft 3.

The surface of the sleeves can be smooth or may be profiled by grooves in longitudinal or cross direction, or perforated. FIGURE 3 shows a longitudinal cross section of a thin-layer vaporizer where the sleeves 6a are provided with openings 7. Portions of the substances will enter the sleeves 6a through these holes 7 and form additional film on their insides. Solids will also be forced through the holes into the sleeves and led off. This species is suitable primarily for systems employing rotating sleeves.

The sleeves can be continuous or in sections lined up end to end on the stretched springs as shown in FIG URES l and 3, but the sections can also be arranged at certain distances from each other and fastened in this position. Care must be taken in this case that the sleeve sections are staggered on the different axles in such manner that they will sweep over the entire inner surface of the vaporizer tube 1.

Another specific species of the oscillating axles is a design in which the sleeves rotate eccentrically about the stretched springs. This is attained by making the di amcter of the stretched springs significantly smaller than the inner diameter of the sleeves as shown by FIGURE 4. An effective eccentricity will be obtained if the ratio of the diameter of the sleeve opening to the diameter of the stretched spring is made 1.2:1 to 2:1, and preferably 1.5:1. Wires that l are taut or' wound into very narrow coils a are the most suitable in connection with this specific design. This design offers the advantage that always a drift will be superimposed, its intensity being a function of the magnitude of the eccentricity resulting from the rolling motion of the sleeves 6. The greater is the eccentricity the greater will be the drift. This species is particularly suitable for vaporization processes where the material to be vaporized is initially of high viscosity and the drift will serve to change continuously the surface of the material. In this case again the oscillations of the axle will increase when the viscosity or the solidification of the material increases. The percussions applied to the vaporizer tube are amplified by the loose seat of the sleeves and Will conform to the base.

The novel oscillating axles are not limited to the arrangement Where the stretched springs are located within the sleeves but the springs, which in this case are most suitably designe-d in the form of coil springs, can also be.wound around sleeves provided with corresponding spiral-shaped recesses. FIGURE 5 shows such species where the recesses are made so deep in the sleeve 6b that the stretched coil spring 5b will not protrude over the cylindrical area of the sleeve. The sleeves are therefore connected fixedly with the stretched springs resulting in a particularly robust, spring-reinforced swinging distributing system.

It is often desirable to provide an unobstructed inner area within the rotor to be utilized for example for the installation of a condenser in order to make the arrangement particularly suitable for the molecular distillation.

FIGURE 6 shows a longitudinal section of such thin layer vaporizer. The shaft journal 3a is connected with the drive shaft 13 by means of a resilient coupling 8, a spring being utilized in this case for the coupling. The shaft journal 3a holds, by means of radial bearing arms 4, the supporting rings 4a which support the entire rotor system. Distributed over the entire length of the rotor are bearing rings 9, arranged at certain distances from each other and connected by rods 10, giving the rotor system the necessary stability.

The supporting rings 4a are provided with tapped holes to receive the bearing pins 11. The pins have a recess for the fastening of the stretched spring 5. The bearing pins 11 are adjustable by means of the tapped hole to be fitted precisely to the inner diameter of the vaporizer tube 1. A lock nut 12 prevents any undesired turning. Supporting rings 4a may be provided not only at the ends but also intermediate the ends of the rotary assembly.

When the system is rotated the rotor will be able to oscillate freely within certain limits, inside the cylindrical vaporizer tube 1. The oscillations are absorbed by the resilient coupling 8 so that the main drive shaft will run smoothly, making it easy to provide effective bearings and seals.

The rods can be utilized to hold deflecting or baffle plates (not illustrated by drawing) to prevent contamination of the condensation product caused by splashes from the vaporizer Wall.

Obviously, it is also possible to combine the individual elements with each other. For example, in case of the last-mentioned species illustrated in FIG. 6 the sleeves 6 can be provided With holes as in FIG. 3, the coil spring 5 can be replaced by a straight taut wire, or the oscillating axle consisting of elements 5 and 6 can be replaced by an oscillating axle consisting of a sleeve 6b and spring 5b in accordance with FIGURE 5.

Since the present invention is concerned only with the means for distributing the liquid'to be evaporated over the wall of the evaporating chamber and for removing deposits therefromonly these parts have been illustrated, it being understood that the complete apparatus may include the usual well known accessories of vaporizing apparatus such as means for rotating the rotor assembly, means for supplying heat, means for applying pressure or vacuum, means for supplying the liquid to be vaporized, means for discharging the evaporated productetc;

I claim:

1. Apparatus for vaporizing liquids comprising an evaporating chamber having a cylindrical inner surface, a rotor assembly mounted to rotate coaxially within said chamber, said rotor assembly comprising a plurality of tensioned flexible cylindrical coil springs, each spring being supported at its opposite ends and extending parallel to the axis of and adjacent to said cylindrical surface and a set of cylindrical sleeves supported end to end by each spring and extending substantially the entire length thereof.

2. Apparatus for vaporizing liquids as defined in claim 1 in which each spring is wound around said sleeves and is embedded in grooves in the surfaces thereof.

3. Apparatus for vaporizing liquids as defined in claim 1 in which said rotor comprises a central shaft coincident with the axis of said cylindrical surface and radial arms carried by said shaft supporting said springs.

4. Apparatus for vaporizing liquids as defined in claim 1 in which said rotor comprises a resiliently coupled rotary shaft at the upper end of said chamber, a ring supported by the inner end of said rotary shaft, a plurality of rods supported at their upper ends by said ring and another ring at the bottom end of said chamber connected to the lower ends of said rods, said springs being supported between said rings.

5. Apparatus for vaporizing liquids as defined in claim 1 in which the tensioned springs are coiled and cylindrical,

6. Apparatus for vaporizing liquids as defined in claim Sin which a set of sleeves surrounds each spring.

7. Apparatus for vaporizing liquids as defined in claim 5 in which said sleeves fit snugly around said springs.

8. Apparatus for vaporizing liquids as defined in claim 5 in which the diameters of said sleeves are substantially greater than the diameters of the springs which they surround.

9. Apparatus for vaporizing liquids as defined in claim 5 in which said sleeves are provided with lateral openings.

References Cited by the Examiner UNITED STATES PATENTS 1,420,645 6/1922 Mabee 159-6 1,955,277 4/1934 Fasting 159-8 X 2,957,138 5/1934 Hasselbach 159-5 2,024,299 12/1935 Metcalfe-Shaw 159-6 2,076,498 4/ 1937 Farwell. 2,460,602 2/1949 Semon 159-6 2,831,665 4/1958 Bairfuss 259-107 2,974,725 3/1961 Samesreuther et al. 159-6 3,058,516 10/1962 Brunk 159-6 3,060,107 10/1962 Smith 159-6 X FOREIGN PATENTS 1,136,982 9/1962 Germany.

330,805 6/1930 Great Britain.

656,605 8/1951 Muller.

NORMAN YUDKOFF, Primary Examiner. 

1. APPARATUS FOR VAPORIZING LIQUIDS COMPRISING AN EVAPORATING CHAMBER HAVING A CYLINDRICAL INNER SURFACE, A ROTOR ASSEMBLY MOUNTED TO ROTATE COAXIALLY WITHIN SAID CHAMBER, SAID ROTOR ASSEMBLY COMPRISING A PLURALITY OF TENSIONED FLEXIBLE CYLINDRICAL COIL SPRINGS, EACH SPRING BEING SUPPORTED AT ITS OPPOSITE ENDS AND EXTENDING PARALLEL TO THE AXIS OF AND ADJACENT TO SAID CYLINDRICAL SURFACE AND A SET OF CYLINDRICAL SLEEVES SUPPORTED END TO END BY EACH SPRING AND EXTENDING SUBSTANTIALLY THE ENTIRE LENGTH THEREOF. 